com.google.caja.util.TypesafeSet.java Source code

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Here is the source code for com.google.caja.util.TypesafeSet.java

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// Copyright (C) 2013 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package com.google.caja.util;

import com.google.common.collect.ImmutableSet;

import java.util.Arrays;
import java.util.Iterator;
import java.util.Set;

/**
 * A set-like object that supports a type-safe {@code contains(T)} method
 * instead of the more error-prone {@code Collection<T>.contains(Object)}.
 *
 * This supports containment checks and iteration, and equality, but no other
 * set or collection operations.
 *
 * @param <T> The type of element.
 */
public final class TypesafeSet<T> implements Iterable<T> {
    private final Set<T> contents;

    private TypesafeSet(Iterable<? extends T> els) {
        this.contents = ImmutableSet.copyOf(els);
    }

    public static final <T> TypesafeSet<T> of(T... els) {
        return new TypesafeSet<T>(Arrays.asList(els));
    }

    public static final <T> TypesafeSet<T> of(Iterable<? extends T> els) {
        return new TypesafeSet<T>(els);
    }

    public boolean contains(T el) {
        return contents.contains(el);
    }

    public Iterator<T> iterator() {
        return contents.iterator();
    }

    public Set<T> asSet() {
        return contents;
    }

    @Override
    public String toString() {
        return contents.toString();
    }

    @Override
    public boolean equals(Object o) {
        return o instanceof TypesafeSet<?> && contents.equals(((TypesafeSet<?>) o).contents);
    }

    @Override
    public int hashCode() {
        return contents.hashCode();
    }
}